[Do valid criteria exist for the evaluation of follicular maturity during hMG stimulation?]

During hMG therapy for ovarian stimulation, the common criteria used to appreciate both follicular growth and granulosa cells maturity are the simultaneous determination of plasma oestradiol levels and ultrasound measurement of the size of the follicles. However such an approach does not take into account that, when administered at pharmacological doses, hMG stimulate the growth of secondary and tertiary follicules and therefore create an extraphysiological hormonal environment. Although the rate of growth is identical between the follicles stimulated by hMG, their development is initiated at different periods of time during the follicular phase. For that reason, it is usual to observe a degree of asynergy in the size and maturation of the different follicles. Moreover, from IVF practice, it becomes evident that, in cycles stimulated by hMG, a dissociation between granulosa cells and oocyte maturation may be present and decreases the predictive value of the hormonal index of granulosa cell maturation. In fact, if the role of the hormones on the follicular growth and on the granulosa cells differentiation is well understood, their implication on growth and meiotic competence of the oocyte is still unknown, at last in human beings.